SEWAGE CONTAMINATION OF OYSTER BEDS. 233 
chart as micrococcus No. 1. It occurs in pairs and short chains of 4 
or 6 elements that vary considerably in size according to the medium 
on which they are cultivated. Grown on gelatin the cocci are con- 
siderably over 1 micron in diameter; in bouillon they are somewhat 
less than 1 micron. This organism was observed in 15 per cent of the 
oysters examined. 
There is a greater variety among the rod forms isolated from the 
plates. An organism closely resembling Ps. fluorescens was found 
in 89 of the 100 samples examined. Another fluorescent bacillus 
occurring in 60 per cent of these plates is referred to on the chart 
as No. 11. This is a nonliquefying, strongly fluorescent organism 
that differs from No. 5 only in certain of its cultural features. These 
three fluorescent bacilli were found repeatedly in the plates made 
from the Wickford oysters. Some plates appeared to contain almost 
pure cultures of Ps. fluorescens and B. rugosus. Bacillus No. 2 was 
found in the intestinal content of 15 of these oysters. It is a small, 
actively motile bacillus that grows well at room temperature and at 
37° C. The presence of a very dilute solution of carbolic acid in the 
culture medium (one drop of a 5 per cent solution to 10 ¢.c. of medium) 
entirely inhibits the growth of this organism. Four unidentified 
species (No. 6) already described among the bacterial flora of the 
Kickemuit River oysters (No. 7, No. 8, and No. 10) were found in 
the plates inoculated from the intestinal content of Wickford oys- 
ters. Bacillus No. 6 was found in 30 plates, No. 7 in 20 plates, and 
the other two in a much less number. B. subtilis, B. vulgatus, and B. 
mesentericus Juscus were isolated from the intestines of these oysters. 
In a word, the bacteria living in oysters taken fresh from pure water 
are common water forms. Ananalysis of the juice of oysters is prac- 
tically the analysis of the water in which the oysters live. The 
stomachs of 60 per cent of the specimens examined appeared to be 
sterile—at least no growth developed in plates inoculated with material 
from this organ. Most of the bacteria found in the stomachs proved 
to be micrococci. On the other hand an abundant growth appeared 
on plates inoculated with material taken from the intestines of oysters 
collected in different sections of the bay. Liquefying organisms 
seemed to predominate, and large numbers of fluorescent bacilli were 
repeatedly observed, but no bacteria in any way resembling sewage 
forms were found. Fora complete list of the bacteria isolated from 
these oysters the reader is referred to the accompanying chart. 
